Delete key from path

Hey there I am looking for some guidance on how to handle deleting of keys from a changeset object.
I am working on a complex form which did have lots of nested arrays. I am trying out flattening the array to track the fields better. This definitely works better, but I cant work out how to delete the whole key / value and get the changes to be tracked.

This is what I have
```
{
metadata: {
fields: ['name','lastName','age']
relatedFields: [
{ id: 1, name: 'foo', value: 'bar'}
]
}
```

Which becomes

```
{
metadata: {
'fields[0]': 'name',
'fields[1]': 'lastName',
'fields[2]': 'age',
relatedFields[0].id: 1,
relatedFields[0].name: 'foo'
relatedFields[0].value: 'bar',
}
```

This makes tracking much easier.

My question. How would I delete `'fields[1]':` I tried ` delete changeset.data['fields[1]']` to no avail